docs: def _get_stddevs(self, C, stddev_types, nsites):
          """
          Compute total standard deviation, see table 4.2, page 50.
          """
          stddevs = []
          for stddev_type in stddev_types:
              assert stddev_type in self.DEFINED_FOR_STANDARD_DEVIATION_TYPES
              if stddev_type == const.StdDev.TOTAL:
                  stddevs.append(C['sigma'] + np.zeros(nsites, dtype=float))
          return stddevs